The Training Program in Environmental Epidemiology seeks to prepare outstanding researchers in environmental epidemiology through rigorous training and research methodology. Currently in its 35th year, this program is the cornerstone of support for students working in environmental epidemiology at the Harvard School of Public Health. The investigators have graduated over 180 professionals who are researchers, teachers, and consultants in environmental epidemiology and related disciplines. Many hold leadership positions in academia, government, and the private sector. Complementing the environmental epidemiology track, the new track in environmental molecular epidemiology, developed to provide trainees with comprehensive exposure in applying molecular genetic and epigenetic techniques to environmental epidemiologic research, is flourishing with trainees and new faculty. Training for both tracks is offered at the pre- and postdoctoral levels; the investigators again request 8 pre- and 4 postdoctoral trainees. Pre-doctoral students in the environmental epidemiology track take courses in epidemiology, exposure analysis, exposure biology, biostatistics, etc. Research credits are obtained through tutorials on current problems in epidemiology and from the completion of a doctoral thesis of substance. The track in environmental molecular epidemiology offers trainees additional courses in molecular biology, genetics, epigenetics, etc., and research opportunities in laboratories dedicated to molecular epidemiology with an emphasis on gene-environment interactions. Pre-doctoral training usually lasts 3 to 5 years; the first 2.5 years are devoted primarily to course work. Most didactic teaching is shared by the Departments of Epidemiology and Environmental Health at the School of Public Health, but also includes a host of affiliates working within the Harvard Medical area. Postdoctoral trainees are exposed to a wide variety of interdisciplinary and integrated intellectual offerings, including didactic instruction, seminars, professional colloquia, meetings, and academic collaboration. Significant independent research usually begins for the postdoctoral fellow in his/her second year and varies in duration depending on the scope of work. The program has been updated according to the NIEHS PA-10-036, with programmatic focus on priority areas and exposures. This program will continue a long history of excellence in training successful researchers in the field of environmental epidemiology at Harvard University.